UC Riverside engineers are developing cheap, energy-efficient lithium-ion batteries for electric vehicles from silicon in diatomaceous earth
Researchers at the University of California, Riverside’s Bourns College of Engineering have developed an inexpensive, energy-efficient way to create silicon-based anodes for lithium-ion batteries from the fossilized remains of single-celled algae called diatoms. The research could lead to the development of ultra-high capacity lithium-ion batteries for electric vehicles and portable electronics.
Titled “Carbon-Coated, Diatomite-Derived Nanosilicon as a High Rate Capable Li-ion Battery Anode,” a paper describing the research was published recently in the journal Scientific Reports. The research was led by Mihri Ozkan, professor of electrical engineering, and Cengiz Ozkan, professor of mechanical engineering. Brennan Campbell, a graduate student in materials science and engineering, was first author on the paper.
Lithium-ion batteries, the most popular rechargeable batteries in electric vehicles and personal electronics, have several major components including an anode, a cathode, and an electrolyte made of lithium salt dissolved in an organic solvent. While graphite is the material of choice for most anodes, its performance is a limiting factor in making better batteries and expanding their applications. Silicon, which can store about 10 times more energy, is being developed as an alternative anode material, but its production through the traditional method, called carbothermic reduction, is expensive and energy-intensive.
To change that, the UCR team turned to a cheap source of silicon—diatomaceous earth (DE)—and a more efficient chemical process. DE is an abundant, silicon-rich sedimentary rock that is composed of the fossilized remains of diatoms deposited over millions of years. Using a process called magnesiothermic reduction, the group converted this low-cost source of Silicon Dioxide (SiO2) to pure silicon nano-particles.
“A significant finding in our research was the preservation of the diatom cell walls—structures known as frustules—creating a highly porous anode that allows easy access for the electrolyte”, Cengiz Ozkan said.
This research is the latest in a series of projects led by Mihri and Cengiz Ozkan to create lithium-ion battery anodes from environmentally friendly materials. Previous research has focused on developing and testing anodes from portabella mushrooms and beach sand.
“Batteries that power electric vehicles are expensive and need to be charged frequently, which causes anxiety for consumers and negatively impacts the sale of these vehicles. To improve the adoption of electric vehicles, we need much better batteries. We believe diatomaceous earth, which is abundant and inexpensive, could be another sustainable source of silicon for battery anodes,” Mihri Ozkan said.
In addition to Mihri and Cengiz Ozkan and Campbell, graduate students Robert Ionescu, Maxwell Tolchin, Kazi Ahmed, Zachary Favors, and Krassimir N. Bozhilov, manager of UCR’s Central Facility for Advanced Microscopy and Microanalysis, also contributed to this research.
A molecule that transports oxygen in blood could be key to developing the next generation of batteries, and in a way that’s environmentally friendly.
Lithium-oxygen (Li-O2) batteries have emerged in recent years as a possible successor to lithium-ion batteries — the industry standard for consumer electronics — due to their potential for holding a charge for a very long time. Electronic devices would go for weeks without charging, for instance; electric cars could travel four to five times longer than the current standard.
But before this could happen, researchers need to make the Li-O2 batteries efficient enough for commercial application and prevent the formation of lithium peroxide, a solid precipitate that covers the surface of the batteries’ oxygen electrodes. One obstacle is finding a catalyst that efficiently facilitates a process known as oxygen evolution reaction, in which lithium oxide products decompose back into lithium ions and oxygen gas.
The Yale lab of Andre Taylor, associate professor of chemical and environmental engineering, has identified a molecule known as heme that could function as a better catalyst. The researchers demonstrated that the heme molecule improved the Li-O2 cell function by lowering the amount of energy required to improve the battery’s charge/discharge cycle times.
The results appear Oct. 19 in Nature Communications. The lead author is Won-Hee Ryu, a former postdoctoral researcher in Taylor’s lab, who is now an assistant professor of chemical and biological engineering at Sookmyung Women’s University in South Korea.
The heme is a molecule that makes up one of the two parts of a hemoglobin, which carries oxygen in the blood of animals. Used in an Li-O2 battery, Ryu explained, the molecule would dissolve into the battery’s electrolytes and act as what’s known as a redox mediator, which lowers the energy barrier required for the electrochemical reaction to take place.
“When you breathe in air, the heme molecule absorbs oxygen from the air to your lungs and when you exhale, it transports carbon dioxide back out,” Taylor said. “So it has a good binding with oxygen, and we saw this as a way to enhance these promising lithium-air batteries.”
The researchers added that their discovery could help reduce the amount of animal waste disposal.
“We’re using a biomolecule that traditionally is just wasted,” said Taylor. “In the animal products industry, they have to figure out some way to dispose of the blood. Here, we can take the heme molecules from these waste products and use it for renewable energy storage.”
Ryu noted that by using recyclable biowaste as a catalyst material, the technology is both effective and could be preferential in developing green energy applications.
Learn more: Blood molecule key to more efficient batteries
Nanomaterial combines attributes of both batteries and supercapacitors
A powerful new material developed by Northwestern University chemist William Dichtel and his research team could one day speed up the charging process of electric cars and help increase their driving range.
An electric car currently relies on a complex interplay of both batteries and supercapacitors to provide the energy it needs to go places, but that could change.
“Our material combines the best of both worlds — the ability to store large amounts of electrical energy or charge, like a battery, and the ability to charge and discharge rapidly, like a supercapacitor,” said Dichtel, a pioneer in the young research field of covalent organic frameworks (COFs).
Dichtel and his research team have combined a COF — a strong, stiff polymer with an abundance of tiny pores suitable for storing energy — with a very conductive material to create the first modified redox-active COF that closes the gap with other older porous carbon-based electrodes.
“COFs are beautiful structures with a lot of promise, but their conductivity is limited,” Dichtel said. “That’s the problem we are addressing here. By modifying them — by adding the attribute they lack — we can start to use COFs in a practical way.”
And modified COFs are commercially attractive: COFs are made of inexpensive, readily available materials, while carbon-based materials are expensive to process and mass-produce.
Dichtel, the Robert L. Letsinger Professor of Chemistry at the Weinberg College of Arts and Sciences, is presenting his team’s findings today (Aug. 24) at the American Chemical Society (ACS) National Meeting in Philadelphia. Also today, a paper by Dichtel and co-authors from Northwestern and Cornell University was published by the journal ACS Central Science.
To demonstrate the new material’s capabilities, the researchers built a coin-cell battery prototype device capable of powering a light-emitting diode for 30 seconds.
The material has outstanding stability, capable of 10,000 charge/discharge cycles, the researchers report. They also performed extensive additional experiments to understand how the COF and the conducting polymer, called poly(3,4-ethylenedioxythiophene) or PEDOT, work together to store electrical energy.
Dichtel and his team made the material on an electrode surface. Two organic molecules self-assembled and condensed into a honeycomb-like grid, one 2-D layer stacked on top of the other. Into the grid’s holes, or pores, the researchers deposited the conducting polymer.
Each pore is only 2.3 nanometers wide, but the COF is full of these useful pores, creating a lot of surface area in a very small space. A small amount of the fluffy COF powder, just enough to fill a shot glass and weighing the same as a dollar bill, has the surface area of an Olympic swimming pool.
The modified COF showed a dramatic improvement in its ability to both store energy and to rapidly charge and discharge the device. The material can store roughly 10 times more electrical energy than the unmodified COF, and it can get the electrical charge in and out of the device 10 to 15 times faster.
“It was pretty amazing to see this performance gain,” Dichtel said. “This research will guide us as we investigate other modified COFs and work to find the best materials for creating new electrical energy storage devices.”
Although rechargeable batteries in smartphones, cars and tablets can be charged again and again, they don’t last forever. Old batteries often wind up in landfills or incinerators, potentially harming the environment. And valuable materials remain locked inside. Now, a team of researchers is turning to naturally occurring fungi to drive an environmentally friendly recycling process to extract cobalt and lithium from tons of waste batteries.
The researchers will present their work today at the 252nd National Meeting & Exposition of the American Chemical Society (ACS). ACS, the world’s largest scientific society, is holding the meeting here through Thursday. It features more than 9,000 presentations on a wide range of science topics.
“The idea first came from a student who had experience extracting some metals from waste slag left over from smelting operations,” says Jeffrey A. Cunningham, Ph.D., the project’s team leader. “We were watching the huge growth in smartphones and all the other products with rechargeable batteries, so we shifted our focus. The demand for lithium is rising rapidly, and it is not sustainable to keep mining new lithium resources,” he adds.
Although a global problem, the U.S. leads the way as the largest generator of electronic waste. It is unclear how many electronic products are recycled. Most likely, many head to a landfill to slowly break down in the environment or go to an incinerator to be burned, generating potentially toxic air emissions.
While other methods exist to separate lithium, cobalt and other metals, they require high temperatures and harsh chemicals. Cunningham’s team is developing an environmentally safe way to do this with organisms found in nature — fungi in this case — and putting them in an environment where they can do their work. “Fungi are a very cheap source of labor,” he points out.
To drive the process, Cunningham and Valerie Harwood, Ph.D., both at the University of South Florida, are using three strains of fungi — Aspergillus niger, Penicillium simplicissimum andPenicillium chrysogenum. “We selected these strains of fungi because they have been observed to be effective at extracting metals from other types of waste products,” Cunningham says. “We reasoned that the extraction mechanisms should be similar, and, if they are, these fungi could probably work to extract lithium and cobalt from spent batteries.”
The team first dismantles the batteries and pulverizes the cathodes. Then, they expose the remaining pulp to the fungus. “Fungi naturally generate organic acids, and the acids work to leach out the metals,” Cunningham explains. “Through the interaction of the fungus, acid and pulverized cathode, we can extract the valuable cobalt and lithium. We are aiming to recover nearly all of the original material.”
Results so far show that using oxalic acid and citric acid, two of the organic acids generated by the fungi, up to 85 percent of the lithium and up to 48 percent of the cobalt from the cathodes of spent batteries were extracted. Gluconic acid, however, was not effective for extracting either metal.
The cobalt and lithium remain in a liquid acidic medium after fungal exposure, Cunningham notes. Now his focus is on how to get the two elements out of that liquid.
“We have ideas about how to remove cobalt and lithium from the acid, but at this point, they remain ideas,” he says. “However, figuring out the initial extraction with fungi was a big step forward.”
Other researchers are also using fungi to extract metals from electronic scrap, but Cunningham believes his team is the only one studying fungal bioleaching for spent rechargeable batteries.
Cunningham, Harwood and graduate student Aldo Lobos are now exploring different fungal strains, the acids they produce and the acids’ efficiencies at extracting metals in different environments.
Learn more: Fungi recycle rechargeable lithium-ion batteries
The Materials Project, run by Berkeley Lab, accelerates innovation by enabling computationally driven materials and battery design.
The Materials Project, a Google-like database of material properties aimed at accelerating innovation, has released an enormous trove of data to the public, giving scientists working on fuel cells, photovoltaics, thermoelectrics, and a host of other advanced materials a powerful tool to explore new research avenues. But it has become a particularly important resource for researchers working on batteries.
Co-founded and directed by Lawrence Berkeley National Laboratory (Berkeley Lab) scientist Kristin Persson, the Materials Project uses supercomputers to calculate the properties of materials based on first-principles quantum-mechanical frameworks. It was launched in 2011 by the U.S. Department of Energy’s (DOE) Office of Science.
In 2012, DOE established the Joint Center for Energy Storage Resarch (JCESR), a DOE Energy Innovation Hub, which significantly enhanced the Materials Project with new simulations of next-generation battery electrodes and liquid organic electrolytes.
“This massive amount of precise data released through the Materials Project will have a profound and lasting impact on the battery research community,” said JCESR Director George Crabtree. “This is a great example of the way Berkeley Lab and other JCESR partners share scientific knowledge to advance the scientific frontier.”
The idea behind the Materials Project is that it can save researchers time by predicting material properties without needing to synthesize the materials first in the lab. It can also suggest new candidate materials that experimentalists had not previously dreamed up. With a user-friendly web interface, users can look up the calculated properties, such as voltage, capacity, band gap, and density, for tens of thousands of materials.
MSU chemists created a material able to enhance a charge rate of li-ion batteries drastically
Nowadays Li-ion batteries power a wide range of electronic devices: mobile phones, tablets, laptops. They became popular in 90s and subsequently ousted widespread nickel-metal hydride batteries.
However, Li-ion batteries suffer a number of disadvantages. For example, their capacity may drop when temperature falls below zero. The price is also discomforting, which is mostly caused by use of expensive lithium-containing materials. For instance, Li-ion batteries make about half a price of a popular electro car Tesla Model S. On the other hand, Li-ion batteries are compact, easy to use and highly capacious, which means that your device would live long having a relatively small battery.
A key element of the Li-ion batteries limiting its capacity is a material used for its cathode. For the majority of the materials their capacity limit has already been reached. Hence, scientists and engineers are actively searching for new cathode materials capable of recharging completely within minutes, operate under high current densities, and store more energy.
One of the most prospective classes of cathode materials for a new generation of Li-ion batteries are fluoride-phosphates of transition metals.
The work directed by Prof. Evgeny Antipov (correspondent member of the Russian Academy of Sciences and the head of the MSU Electrochemistry Department) was carried out by a team of MSU research scientists together with their Russian and Belgian colleagues. It was devoted to creation of a new high-power cathode material based on a fluoride-phosphate of vanadium and potassium for Li-ion batteries. The results were published in Chemistry of Materials(current IF — 8.354)
‘The work is based on a simple idea of geometric and crystal-chemical conformity of ionic sublattices,’ — says Stanislav Fedotov, one of the authors, junior research scientist at Electrochemistry Department, Faculty of Chemistry, MSU.
The scientists succeeded to stabilize a unique crystal structure, which provides a fast transport of lithium ions through spatial cavities and channels. Consequently, the suggested cathode material demonstrated high charge/discharge rates (down to 90 seconds) retaining more than 75% of an initial specific capacity. With its morphology and composition optimized, this material may become a serious contender to such well-known and commercialized high-power cathode materials as NaSICON.
According to the authors, the results of the presented work may not only open up ample opportunities in searching and further synthesis of new cathode materials for Li-ion batteries, but also promote the development of a new battery type where a role of a mobile ion (a charge carrier) would be performed by potassium ions instead of lithium.
‘It is assumed that such batteries would not only deliver high energy density, but would also be economically attractive due to a replacement of expensive lithium-containing components with cheaper and hence affordable potassium-containing analogues’ — explains Stanislav Fedotov.
Learn more: New material to enhance battery life